2x - 15 = -11 - ( -16 )
2x - 15 = -11 + 16
2x - 15 = 5
2x = 5 + 15
2x = 20
x = 20 : 1
x = 10
Vậy x = 10
7 - 2x = -37 - ( -26 )
7 - 2x = -37 + 26
7 - 2x = -11
2x = 7 - ( - 11 )
2x = 7+ 11
2x = 18
x = 18 : 2
x = 9
Vậy x = 9
| x + 7 | = 9
TH1 :
x + 7 = 9
=> x = 9 - 7
=> x = 2
TH2 :
x - 7 = -9
=> x = -9 - 7
=> x = - 9 + ( -7 )
=> x = -16
Vậy x = 2 và x = -16
Câu cuối bn tự làm nha! ^-^
2x-15=-11-(-16)
2x-15= -11+16
2x-15=5
2x=5+15
2x=20
x=20:2
x=10
\(2x-15=-11-\left(-16\right)\)
\(\Leftrightarrow2x-15=5\)
\(\Leftrightarrow2x=5+15\)
\(\Leftrightarrow2x=20\)
\(\Leftrightarrow x=20\div2\)
\(\Leftrightarrow x=10\)
\(-7-2x=-37-\left(-26\right)\)
\(\Leftrightarrow-7-2x=-11\)
\(\Leftrightarrow2x=-7+11\)
\(\Leftrightarrow2x=4\)
\(\Leftrightarrow x=\frac{4}{2}\)
\(\Leftrightarrow x=2\)
\(\left|x+7\right|=9\)
\(\Leftrightarrow\orbr{\begin{cases}x+7=-9\\x+7=9\end{cases}}\)
Trường hợp : \(x+7=-9\)
\(\Leftrightarrow x=-9-7\)
\(\Leftrightarrow x=-16\)
Trường hợp : \(x+7=9\)
\(\Leftrightarrow x=9-7\)
\(\Leftrightarrow x=2\)
Vậy \(x\in\left\{-16;2\right\}\)
\(\left|x-2\right|< 3\)
\(\Leftrightarrow\orbr{\begin{cases}x-2< 3\\2-x< 3\end{cases}}\)
Trường hợp : \(x-2< 3\)
\(\Leftrightarrow x< 3+2\)
\(\Leftrightarrow x< 5\)
Trường hợp : \(2-x< 3\)
\(\Leftrightarrow x< 2-3\)
\(\Leftrightarrow x< -1\)
\(\Rightarrow x\in Z^-\)
